Welcome to WIFI Antennas

Register now to gain access to all of our features. Once registered and logged in, you will be able to contribute to this site by submitting your own content or replying to existing content. You'll be able to customize your profile, receive reputation points as a reward for submitting content, while also communicating with other members via your own private inbox, plus much more! This message will be removed once you have signed in.

swarg_eu

DVB-T2 Front End

Selfmade RF frontend for Video signal (Analog, DVB-T, DVB-T2, CATV) amplification in a 75 Ohm system.

 

The RF frontend contains the following building blocks:

4-Way Wilkinson power combiner - combines the signal from 4 antennas (~6dB gain)

bandpass filter - eliminates the interfering radio signals (FM...)

low noise amplifier with a voltage regulator - for sensitivity improvement (~21dB gain, NF~1dB )

 

Interconnections: 

4    F type connector 75 Ohm inputs (antenna) 

1    F type connector 75 Ohm output (receiver side), requires a bias voltage in the range of 6-20 VDC and ~60 mA (for example: ZS300 antenna power injector )

 

Technical data:

Frequency range  from ~460 to ~880 MHz

Noise figure >2,5 dB (including insertion losses)

Gain <25 dB (including insertion losses and combiner gain)

P1dB ~19dBm

Max Pin 17dBm

Size ~250x120x25 mm

 

The use of this RF frontend is recommended in one of the following scenarios:

the picture is pixelated but you are already using a high gain antenna and amplifier

you are in a high power RF environment, Amateur Radio, FM radio is attenuated by more than 80dB ...

you want to combine the signal from multiple directions to a single cable (signal quality will/can be reduced)

 

Basic knowledge in antenna (phase) arrays is recommended to exploit the benefits of the RF frontend. 

Protective housing not included.

Antennas not included.

Power injector not included.

Coax cable not included.

 

Test results (scenario with a pixelated picture and high power RF environment)

 

DVB-T2 Transmitter side cordinates  45,89938 N; 15,94786 E;

DVB-T2 Reciever side coordinates  44,47105 N; 17,97297 E;

Link distance ~225 km, no line of sight.

 

Receiver side 2x2 antenna array with Triplex Loga Iskra P-47N (without an amplifier, marked on radio tower picture), connected with ~1m RG-6/U coax cable (length variation between antennas <1cm) to RF frontend.

Received signal strength (SNR) above the threshold including fading effects (SNR range 29-37 dB).

Successful elimination of interfering radio signals (see measured transmission response) on the receiver side (4 FM station with 400 W  ....)

 

Free worldwide shipping with DHL.

20200617_170951.jpg

20200617_171000.jpg

IMG-20200523-WA0000.jpeg

Inked20200523_144632_LI.jpg

Link.png

20200517_173405.jpg

2 people like this

Share this post


Link to post
Share on other sites

Update,

Today I replaced an old front end and got additional 1.5~2 dB.

The old one had an improvised shielding 

20200813_105751.jpg

20200813_110347.jpg

20200813_105730.jpg

IMG-d9b620c58ff9a44a0c54c0e183180891-V.jpg

1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

How are the signals COMBINED...?

it's some kind of diversity or just added Gain...(like a Single antenna with 6dbi more...or so...)

Edited by clanon

Share this post


Link to post
Share on other sites

Combined via 3 x wilkinson splitter

2x antenna on wilkinson

2x wilkinson on wilkinson 

Its just added 6dBi gain by combining the 4 antennas to a 2x2 array

 

1 person likes this

Share this post


Link to post
Share on other sites

,,, for the frequencies of 1.7 --- 2.7 GHz a splitter can be built...???

Share this post


Link to post
Share on other sites

,,,swarg_eu ,you can post the hfss* file with a splitter on the frequencies 1.7-2.7GHz...???

Share this post


Link to post
Share on other sites

75 or 50 ohm system?

2 or 4 way splitter?

Is FR4 1.6 mm ok?

Share this post


Link to post
Share on other sites

,,yes ...!!!

-50 Ohm system--4 way splitter---FR4 1,5 mm

Share this post


Link to post
Share on other sites

finally got the time for the splitter

 

version 1 - a combination of Wilkinson and  impedance transformer

isolation >10 dB between the 4-antenna ports

VSWR_v1.png

 

version 2 - Wilkinson (the 50 Ohm line between the splitters is long and introduces some side effects in S33)

isolation > 20dB between the 4-antenna ports

VSWR_v2.png

 

for both versions, the GND VIA connection is modeled as a solid in the substrate (faster simulation), port 1 antenna input port 3 combiner output 

4-way_v1_TOP.dxf

4-way_v1_VIA.dxf

4-way_v2_TOP.dxf

4-way_v2_VIA.dxf

2 people like this

Share this post


Link to post
Share on other sites

,,,thanks Swarg_eu...!!!

,, so V2, is better ... ???

 

897.jpg

1 person likes this

Share this post


Link to post
Share on other sites

,,,hi buddy...!!!

,,,you can also make a 4-way Wilkinson with an impedance of 75 Ohm...???

Share this post


Link to post
Share on other sites

,,,thanks swarg_eu,can you put these dimensions, please ... !!!

screenshot_2011.jpg

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now